CF lung disease is characterized by increased mucus production, chronic bronchial infection, and inadequate clearance of airways secretions, leading to progressive respiratory failure and death. The mechanism by which CF causes these abnormalities are unknown, but probably relate to defects in mucociliary clearance, a process that depends on the quantity, composition, and viscoelastic properties of mucus. Critical to the rational development of effective gene therapies for cystic fibrosis lung disease is clear understanding of its pathophysiology. In this proposal we attempt to delineate primary pathogenic abnormalities in mucus responsible for lung disease in CF by developing model systems by which alterations in mucus produced by surface epithelium and submucosal glands can be studied. To this end we have utilized the human bronchial xenograft model to study the extent of sulfation of mucus-derived glycoproteins from CF and non-CF tissues. Purified populations of primary surface bronchial epithelial and submucosal glands cells will be used to generate xenografts with and without submucosal glands. By comparing the extent of NaS35O4 and H3- glucosamine incorporation into mucus produced from xenografts composed of primarily surface epithelial cells to those which also contain submucosal glands, we will begin to delineate differences in the biochemical alteration of mucus produced by epithelia at these two sites. Using adenoviral and retroviral recombinant vectors which contain the CFTR and lacZ transgenes we will attempt to correct post-translational defects in CF mucus produced by surface epithelium and/or submucosal glands in an attempt to address relevant questions as to the efficacy of gene therapy of mucus defects in CF epithelia.